Uncooled infrared (IR) sensors are larger and more expensive than visible chip cameras, making them too large and unaffordable for low cost sensing applications. The IR focal plane portion is fabricated with bolometers integrated onto a die which also includes peripheral signal processing circuits. This decreases the available area for bolometers. While each die is large enough to accommodate both bolometers and other circuits, there are fewer die per wafer, driving up total cost. With one die hosting both the bolometers and the signal processing, the bolometer fill factor is less than 70% when leaving area for signal processing circuits. The wafer processing for the signal circuits requires more expensive silicon manufacturing processes than required for addressing bolometers alone. However, the signal circuit area is typically only 30% of total die area. Again, increasing the total cost.
There is a need for lower cost uncooled IR focal plane array sensors and manufacturing methods.